This invention relates to an adjustment device for adjusting a vehicle seat component.
Such adjustment device includes                a rotary fitting for adjusting the vehicle seat component with a first fitting part and a second fitting part pivotally mounted with respect to the first fitting part,        a drive device connected with the rotary fitting for driving the rotary fitting, and        an adjustment element of the drive device for actuating the drive device.        
The drive device is formed to transmit a force present on the adjustment element on the drive side for adjusting the vehicle seat component to the rotary fitting, but to block a force present on the rotary fitting on the output side in the manner of a load moment lock.
In an adjustment device known from DE 10 2005 028 779 B4, which is formed as rotary fitting for a backrest inclination adjuster of a backrest of a vehicle seat, a first fitting part connected with a seat part of the vehicle seat is coupled via a transmission with a second fitting part connected with the backrest such that by rotating a hand wheel the first fitting part can be shifted relative to the second fitting part. Via the hand wheel an adjustment force can be introduced into the rotary fitting, as a result of which the two fitting parts are shifted relative to each other.
To prevent that when a force is present on the rotary fitting on the output side, i.e. for example when the backrest is loaded by a vehicle occupant, the adjustment device is shifted, DE 10 2005 028 779 B4 provides a so-called wrap spring brake with a wrap spring which frictionally contacts a cylindrical housing in the presence of an output-side force and hence introduces the output-side force into the stationary seat frame. However, if an adjustment force is present on the hand wheel on the drive side, the wrap spring is released from its frictional contact, so that the adjustment device can be shifted.
Other forms of adjustment devices with a wrap spring brake are known from DE 40 23 824 C3 and from DE 36 24 018 A1.
By using a wrap spring brake, the shifting of an adjustment device by a force present on the output side can reliably be prevented. In the released condition with actuated wrap spring, a wrap spring brake however also has a comparatively large frictional moment, so that the shifting of the adjustment device requires a comparatively great effort and in addition the wear is increased.